The object of the invention is directed to a method for forming a pipe joint.
In connection with pneumatic material conveying systems, metal pipes are often used in the conveying piping. Particularly in large systems, in which the conveying distances of the material are long, the conveying pipings, more particularly the trunk pipings, can, in terms of their length, be formed into quite long, typically a number of kilometers long, conveying pipings, in which typically a number of joints must be formed between pipe sections. In these, there are often also cases in which it is desired to join metal pipe parts to a pipe part of some other material, e.g. to a pipe part of a plastic material.
In conveying pipings, particularly those formed from plastic pipes or from plastic composite pipes, bushing joints can generally be used for joining different pipe parts end-to-end to each other. The point of connection is placed into the bushing, i.e. into the sleeve part, in such a way that the ends of the pipe parts to be joined together are inside the bushing and the bushing is thus around the point of connection extending in the longitudinal direction of the pipes some distance from the point of connection in both directions. The bushing part or the section to be connected of the pipe part is provided with thermal resistors or corresponding, in which case when forming the joint electric current is conducted to the resistors, in which case the resistors heat up and a joint is formed between the sleeve part and the pipe parts. Thermoplastic pipe joints of the type described above are described e.g. in the publications U.S. Pat. No. 2,739,829, U.S. Pat. No. 4,530,521 and U.S. Pat. No. 4,906,313.
The aim of the present invention is to achieve a completely new type of solution for a pipe joint, by means of which the problems of prior-art solutions can be avoided. One important aim is to achieve a pipe joint solution applicable to the conveying pipings of pneumatic waste transporting systems. Yet another aim is to achieve a solution for conveying piping, which is formed partly from plastic material or from plastic composite material and which comprises pipe sections of other material, by means of which solution the problems of the state of the art are avoided.
Yet another aim is to achieve a solution for joining the pipe sections of conveying piping, in which solution pipe sections of different material can be used.